Titanosaurs were a diverse group of sauropod dinosaurs which included Saltasaurus and Isisaurus. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still thriving at the time of the extinction event at the end of the Cretaceous; the group includes the largest land animals known to have existed, such as Patagotitan—estimated at 37 m long with a weight of 69 tonnes —and the comparably sized Argentinosaurus and Puertasaurus from the same region. The group's name alludes to the mythological Titans of Ancient Greece, via the type genus Titanosaurus. Together with the brachiosaurids and relatives, titanosaurs make up the larger clade Titanosauriformes. Titanosaurs had small heads when compared with other sauropods; the head was wide, similar to the heads of Camarasaurus and Brachiosaurus but more elongated. Their nostrils were large and they all had crests formed by these nasal bones, their teeth were either somewhat spatulate or like pegs or pencils, but were always small.
Their necks were of average length, for sauropods, their tails were whip-like, but not as long as in the diplodocids. While the pelvis was slimmer than some sauropods, the pectoral was much wider, giving them a uniquely'wide-gauged' stance; as a result, the fossilised trackways of titanosaurs are distinctly broader than other sauropods. Their forelimbs were stocky, longer than their hind limbs, their vertebrae were solid. Their spinal column was more flexible, so they were more agile than their cousins and better at rearing up. Unlike other sauropods, some titanosaurs had no digits or digit bones, walked only on horseshoe-shaped "stumps" made up of the columnar metacarpal bones. From skin impressions found with the fossils, it has been determined that the skin of many titanosaur species was armored with a small mosaic of small, bead-like scales around a larger scale. One species, has been discovered with bony plates, like the ankylosaurs. Studies published in 2011 indicate that titanosaurs such as Rapetosaurus, may have used the osteoderms common in the various genera for storing minerals during harsh changes in climate, such as drought.
While they were all huge, many were average in size compared with the other giant dinosaurs. There were some island-dwelling dwarf species such as Magyarosaurus the result of allopatric speciation and insular dwarfism; the family Titanosauridae was once used for derived titanosaurs, but Wilson and Upchurch found the type genus Titanosaurus dubious based on the figures and original description. Weishampel et al. in the second edition of The Dinosauria did not use the family Titanosauridae, instead used several smaller titanosaur families such as Saltasauridae and Nemegtosauridae, coining Lithostrotia for derived titanosaurs. A handful of Argentine sauropod workers, continue to use Titanosauridae for titanosaurs now placed in Lithostrotia. In the second edition of The Dinosauria, the clade Titanosauria was defined as all sauropods closer to Saltasaurus than to Brachiosaurus. Subsequent cladistic analyses have defined Titanosauria as including Saltasaurus but not Euhelopus or Brachiosaurus. Relationships within the Titanosauria have been variable from study to study, complicated by the fact that clade and rank names have been applied inconsistently by various scientists.
One possible cladogram is presented here, follows a 2007 analysis by Calvo and colleagues. The authors notably used the family Titanosauridae in a broader fashion than other recent studies, coined the new clade name Lognkosauria. In the description of Mansourasaurus, Sallam et al. published a phylogenetic analysis of Titanosauria including the most taxa of any analysis of the clade. The relationships within Titanosauria can be seen below. Fossilized dung associated with late Cretaceous titanosaurids has revealed phytoliths, silicified plant fragments, that offer clues to a broad, unselective plant diet. Besides the plant remains that might have been expected, such as cycads and conifers, discoveries published in 2005 revealed an unexpectedly wide range of monocotyledons, including palms and grasses, including ancestors of rice and bamboo, which has given rise to speculation that herbivorous dinosaurs and grasses co-evolved. A large titanosaurid nesting ground was discovered in Auca Mahuevo, in Patagonia and another colony has been discovered in Spain.
Several hundred female saltasaurs dug holes with their back feet, laid eggs in clutches averaging around 25 eggs each, buried the nests under dirt and vegetation. The small eggs, about 11–12 centimetres in diameter, contained fossilised embryos, complete with skin impressions; the impressions showed. The huge number of individuals gives evidence of herd behavior, along with their armor, could have helped provide protection against large predators such as Abelisaurus; the titanosaurs were the last great group of sauropods, which existed from about 136 to 66 million years ago, before the Cretaceous–Paleogene extinction event, were the dominant herbivores of their time. The fossil evidence suggests they replaced the other sauropods, like the diplodocids and the brachiosaurids, which died out between the late Jurassic and the mid-Cretaceous Periods. Titanosaurs were widespread. In December 2011, Argentine scientists announced titanosaur fossils had been found on Antarctica—meaning that titanosaur fossils
Sauropoda, or the sauropods, are a clade of saurischian dinosaurs. They had long necks, long tails, small heads, four thick, pillar-like legs, they are notable for the enormous sizes attained by some species, the group includes the largest animals to have lived on land. Well-known genera include Brachiosaurus, Diplodocus and Brontosaurus. Sauropods first appeared in the late Triassic Period, where they somewhat resembled the related group "Prosauropoda". By the Late Jurassic, sauropods had become widespread. By the Late Cretaceous, those groups had been replaced by the titanosaurs, which had a near-global distribution. However, as with all other non-avian dinosaurs alive at the time, the titanosaurs died out in the Cretaceous–Paleogene extinction event. Fossilised remains of sauropods have been found on every continent, including Antarctica; the name Sauropoda was coined by O. C. Marsh in 1878, is derived from Greek, meaning "lizard foot". Sauropods are one of the most recognizable groups of dinosaurs, have become a fixture in popular culture due to their large sizes.
Complete sauropod fossil finds are rare. Many species the largest, are known only from isolated and disarticulated bones. Many near-complete specimens lack tail tips and limbs. Sauropods were herbivorous quite long-necked quadrupeds with spatulate teeth, they had tiny heads, massive bodies, most had long tails. Their hind legs were thick and powerful, ending in club-like feet with five toes, though only the inner three bore claws, their forelimbs were rather more slender and ended in pillar-like hands built for supporting weight. Many illustrations of sauropods in the flesh miss these facts, inaccurately depicting sauropods with hooves capping the claw-less digits of the feet, or more than three claws or hooves on the hands; the proximal caudal vertebrae are diagnostic for sauropods. The sauropods' most defining characteristic was their size; the dwarf sauropods were counted among the largest animals in their ecosystem. Their only real competitors in terms of size are the rorquals, such as the blue whale.
But, unlike whales, sauropods were terrestrial animals. Their body structure did not vary as much as other dinosaurs due to size constraints, but they displayed ample variety. Some, like the diplodocids, possessed tremendously long tails, which they may have been able to crack like a whip as a signal or to deter or injure predators, or to make sonic booms. Supersaurus, at 33 to 34 metres long, was the longest sauropod known from reasonably complete remains, but others, like the old record holder, were extremely long; the holotype vertebra of Amphicoelias fragillimus may have come from an animal 58 metres long. However, a research published in 2015 speculated that the size estimates of A. fragillimus may have been exaggerated. The longest dinosaur known from reasonable fossils material is Argentinosaurus huinculensis with length estimates of 25 metres to 39.7 metres. The longest terrestrial animal alive today, the reticulated python, only reaches lengths of 6.95 metres. Others, like the brachiosaurids, were tall, with high shoulders and long necks.
Sauroposeidon was the tallest, reaching about 18 metres high, with the previous record for longest neck being held by Mamenchisaurus. By comparison, the giraffe, the tallest of all living land animals, is only 4.8 to 5.5 metres tall. The best evidence indicates that the most massive were Argentinosaurus, Alamosaurus, Antarctosaurus. There was poor evidence that so-called Bruhathkayosaurus, might have weighed over 175 metric tons but this has been questioned; the weight of Amphicoelias fragillimus was estimated at 122.4 metric tons but 2015 research argued that these estimates may have been exaggerated. The largest land animal alive today, the Savannah elephant, weighs no more than 10.4 metric tons. Among the smallest sauropods were the primitive Ohmdenosaurus, the dwarf titanosaur Magyarosaurus, the dwarf brachiosaurid Europasaurus, 6.2 meters long as a fully-grown adult. Its small stature was the result of insular dwarfism occurring in a population of sauropods isolated on an island of the late Jurassic in what is now the Langenberg area of northern Germany.
The diplodocoid sauropod Brachytrachelopan was the shortest member of its group because of its unusually short neck. Unlike other sauropods, whose necks could grow to up to four times the length of their backs, the neck of Brachytrachelopan was shorter than its backbone. On or shortly before 29 March 2017 a sauropod footprint about 5.6 feet long was found at Walmadany in the Kimberley Region of Western Australia. The report said; as massive quadrupeds, sauropods developed specialized graviportal limbs. The hind feet were broad, retained three claws in most species. Unusual compared with other animals were the modified front feet; the front feet of sauropods were dissimilar from those of modern
In zoological nomenclature, a type species is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e. the species that contains the biological type specimen. A similar concept is used for suprageneric groups called a type genus. In botanical nomenclature, these terms have no formal standing under the code of nomenclature, but are sometimes borrowed from zoological nomenclature. In botany, the type of a genus name is a specimen, the type of a species name; the species name that has that type can be referred to as the type of the genus name. Names of genus and family ranks, the various subdivisions of those ranks, some higher-rank names based on genus names, have such types. In bacteriology, a type species is assigned for each genus; every named genus or subgenus in zoology, whether or not recognized as valid, is theoretically associated with a type species. In practice, there is a backlog of untypified names defined in older publications when it was not required to specify a type.
A type species is both a concept and a practical system, used in the classification and nomenclature of animals. The "type species" represents the reference species and thus "definition" for a particular genus name. Whenever a taxon containing multiple species must be divided into more than one genus, the type species automatically assigns the name of the original taxon to one of the resulting new taxa, the one that includes the type species; the term "type species" is regulated in zoological nomenclature by article 42.3 of the International Code of Zoological Nomenclature, which defines a type species as the name-bearing type of the name of a genus or subgenus. In the Glossary, type species is defined as The nominal species, the name-bearing type of a nominal genus or subgenus; the type species permanently attaches a formal name to a genus by providing just one species within that genus to which the genus name is permanently linked. The species name in turn is fixed, to a type specimen. For example, the type species for the land snail genus Monacha is Helix cartusiana, the name under which the species was first described, known as Monacha cartusiana when placed in the genus Monacha.
That genus is placed within the family Hygromiidae. The type genus for that family is the genus Hygromia; the concept of the type species in zoology was introduced by Pierre André Latreille. The International Code of Zoological Nomenclature states that the original name of the type species should always be cited, it gives an example in Article 67.1. Astacus marinus Fabricius, 1775 was designated as the type species of the genus Homarus, thus giving it the name Homarus marinus. However, the type species of Homarus should always be cited using its original name, i.e. Astacus marinus Fabricius, 1775. Although the International Code of Nomenclature for algae and plants does not contain the same explicit statement, examples make it clear that the original name is used, so that the "type species" of a genus name need not have a name within that genus, thus in Article 10, Ex. 3, the type of the genus name Elodes is quoted as the type of the species name Hypericum aegypticum, not as the type of the species name Elodes aegyptica.
Glossary of scientific naming Genetypes – genetic sequence data from type specimens. Holotype Paratype Principle of Typification Type Type genus
Binomial nomenclature called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomen, binominal name or a scientific name; the first part of the name – the generic name – identifies the genus to which the species belongs, while the second part – the specific name or specific epithet – identifies the species within the genus. For example, humans belong within this genus to the species Homo sapiens. Tyrannosaurus rex is the most known binomial; the formal introduction of this system of naming species is credited to Carl Linnaeus beginning with his work Species Plantarum in 1753. But Gaspard Bauhin, in as early as 1623, had introduced in his book Pinax theatri botanici many names of genera that were adopted by Linnaeus; the application of binomial nomenclature is now governed by various internationally agreed codes of rules, of which the two most important are the International Code of Zoological Nomenclature for animals and the International Code of Nomenclature for algae and plants.
Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in the terminology they use and in their precise rules. In modern usage, the first letter of the first part of the name, the genus, is always capitalized in writing, while that of the second part is not when derived from a proper noun such as the name of a person or place. Both parts are italicized when a binomial name occurs in normal text, thus the binomial name of the annual phlox is now written as Phlox drummondii. In scientific works, the authority for a binomial name is given, at least when it is first mentioned, the date of publication may be specified. In zoology "Patella vulgata Linnaeus, 1758"; the name "Linnaeus" tells the reader who it was that first published a description and name for this species of limpet. "Passer domesticus". The original name given by Linnaeus was Fringilla domestica; the ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, although nomenclatorial catalogs include such information.
In botany "Amaranthus retroflexus L." – "L." is the standard abbreviation used in botany for "Linnaeus". "Hyacinthoides italica Rothm. – Linnaeus first named this bluebell species Scilla italica. The name is composed of two word-forming elements: "bi", a Latin prefix for two, "-nomial", relating to a term or terms; the word "binomium" was used in Medieval Latin to mean a two-term expression in mathematics. Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name, from one to several words long. Together they formed a system of polynomial nomenclature; these names had two separate functions. First, to designate or label the species, second, to be a diagnosis or description. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; such "polynomial names" may sometimes look like binomials, but are different. For example, Gerard's herbal describes various kinds of spiderwort: "The first is called Phalangium ramosum, Branched Spiderwort.
The other... is aptly termed Phalangium Ephemerum Virginianum, Soon-Fading Spiderwort of Virginia". The Latin phrases are short descriptions, rather than identifying labels; the Bauhins, in particular Caspar Bauhin, took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words. The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linné, more known by his Latinized name Carl Linnaeus, it was in his 1753 Species Plantarum that he first began using a one-word "trivial name" together with a generic name in a system of binomial nomenclature. This trivial name is what is now known as specific name; the Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word. Linnaeus's trivial names introduced an important new idea, namely that the function of a name could be to give a species a unique label; this meant. Thus Gerard's Phalangium ephemerum virginianum became Tradescantia virgi
Saurischia is one of the two basic divisions of dinosaurs. ‘Saurischia’ translates to lizard-hipped. In 1888, Harry Seeley classified dinosaurs into two orders, based on their hip structure, though today most paleontologists classify Saurischia as an unranked clade rather than an order. All carnivorous dinosaurs are traditionally classified as saurischians, as are all of the birds and one of the two primary lineages of herbivorous dinosaurs, the sauropodomorphs. At the end of the Cretaceous Period, all saurischians except the birds became extinct in the course of the Cretaceous–Paleogene extinction event. Birds, as direct descendants of one group of theropod dinosaurs, are a sub-clade of saurischian dinosaurs in phylogenetic classification. Saurischian dinosaurs are traditionally distinguished from ornithischian dinosaurs by their three-pronged pelvic structure, with the pubis pointed forward; the ornithischians' pelvis is arranged with the pubis rotated backward, parallel with the ischium also with a forward-pointing process, giving a four-pronged structure.
The saurischian hip structure led Seeley to name them "lizard-hipped" dinosaurs, because they retained the ancestral hip anatomy found in modern lizards and other reptiles. He named ornithischians "bird-hipped" dinosaurs because their hip arrangement was superficially similar to that of birds, though he did not propose any specific relationship between ornithischians and birds. However, in the view which has long been held, this "bird-hipped" arrangement evolved several times independently in dinosaurs, first in the ornithischians in the lineage of saurischians including birds, lastly in the therizinosaurians; this would be an example of convergent evolution, therizinosaurians, ornithischian dinosaurs all developed a similar hip anatomy independently of each other as an adaptation to their herbivorous or omnivorous diets. In his paper naming the two groups, Seeley reviewed previous classification schemes put forth by other paleontologists to divide up the traditional order Dinosauria, he preferred one, put forward by Othniel Charles Marsh in 1878, which divided dinosaurs into four orders: Sauropoda, Theropoda and Stegosauria.
Seeley, wanted to formulate a classification that would take into account a single primary difference between major dinosaurian groups based on a characteristic that differentiated them from other reptiles. He found this in the configuration of the hip bones, found that all four of Marsh's orders could be divided neatly into two major groups based on this feature, he placed the Stegosauria and Ornithopoda in the Ornithischia, the Theropoda and Sauropoda in the Saurischia. Furthermore, Seeley used this major difference in the hip bones, along with many other noted differences between the two groups, to argue that "dinosaurs" were not a natural grouping at all, but rather two distinct orders that had arisen independently from more primitive archosaurs; this concept that "dinosaur" was an outdated term for two distinct orders lasted many decades in the scientific and popular literature, it was not until the 1960s that scientists began to again consider the possibility that saurischians and ornithischians were more related to each other than they were to other archosaurs.
Although his concept of a polyphyletic Dinosauria is no longer accepted by most paleontologists, Seeley's basic division of the two dinosaurian groups has stood the test of time, has been supported by modern cladistic analysis of relationships among dinosaurs. One alternative hypothesis challenging Seeley's classification was proposed by Robert T. Bakker in his 1986 book The Dinosaur Heresies. Bakker's classification separated the theropods into their own group and placed the two groups of herbivorous dinosaurs together in a separate group he named the Phytodinosauria; the Phytodinosauria hypothesis was based on the supposed link between ornithischians and prosauropods, the idea that the former had evolved directly from the latter by way of an enigmatic family that seemed to possess characters of both groups, the segnosaurs. However, it was found that segnosaurs were an unusual type of herbivorous theropod saurischian related to birds, the Phytodinosauria hypothesis fell out of favor. A 2017 study by Dr Matthew Grant Baron, Dr David B. Norman and Prof. Paul M. Barrett did not find support for a monophyletic Saurischia, according to its traditional definition.
Instead, the group was found to be paraphyletic, with Theropoda removed from the group and placed as the sister group to the Ornithischia in the newly defined clade Ornithoscelida. As a result, the authors redefined Saurischia as "the most inclusive clade that contains D. carnegii, but not T. horridus", resulting in a clade containing only the Sauropodomorpha and Herrerasauridae
The Maastrichtian is, in the ICS geologic timescale, the latest age of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, of the Mesozoic era or erathem. It spanned the interval from 72.1 to 66 million years ago. The Maastrichtian was succeeded by the Danian. At the end of this period, there was a mass extinction known as the Cretaceous–Paleogene extinction event. At this extinction event, many recognized groups such as non-avian dinosaurs and mosasaurs, as well as many other lesser-known groups, died out; the cause of the extinction is most linked to an asteroid about 10 to 15 kilometres wide colliding with Earth at the end of the Cretaceous. The Maastrichtian was introduced into scientific literature by Belgian geologist André Hubert Dumont in 1849, after studying rock strata of the Chalk Group close to the Dutch city of Maastricht; these strata are now classified as the Maastricht Formation - both formation and stage derive their names from the city. The Maastricht Formation is known for its fossils from this age, most notably those of the giant sea reptile Mosasaurus, which in turn derives its name from the Dutch city.
The base of the Maastrichtian stage is at the first appearance of ammonite species Pachydiscus neubergicus. At the original type locality near Maastricht, the stratigraphic record was found to be incomplete. A reference profile for the base was appointed in a section along the Ardour river called Grande Carrière, close to the village of Tercis-les-Bains in southwestern France; the top of the Maastrichtian stage is defined to be at the iridium anomaly at the Cretaceous–Paleogene boundary, characterised by the extinction of many groups of life, such as certain foraminifers and calcareous nanoplankton, all ammonites and belemnites, etc. The Maastrichtian is subdivided into two substages and three ammonite biozones; the biozones are: zone of Anapachydiscus terminus zone of Anapachydiscus fresvillensis zone of Pachydiscus neubergicus till Pachydiscus epiplectusThe Maastrichtian is coeval with the Lancian North American Land Mammal Age. The following are summaries of the characteristics of specific Maastrichtian aged formations.
The Bearpaw Formation called the Bearpaw Shale, is a sedimentary rock formation found in northwestern North America. It is exposed in the U. S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, east of the Rocky Mountains. It overlies the older Two Medicine, Judith River and Dinosaur Park Formations, is in turn overlain by the Horseshoe Canyon Formation in Canada and the Fox Hills Sandstone in Montana. To the east and south it blends into the Pierre Shale. A marine formation composed of shale, it represents the last major expansion of the Western Interior Seaway before it receded from northwestern North America by the end of the Cretaceous Period, it includes well-preserved ammonite fossils. Other fossils found in this formation include many types of shellfish, bony fish, rays and marine reptiles like mosasaurs and sea turtles; the occasional dinosaur remains have been discovered from carcasses washed out to sea. The Hell Creek Formation is an intensely studied division of Upper Cretaceous to lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana.
The Hell Creek Formation occurs in badlands of eastern Montana and portions of North Dakota, South Dakota, Wyoming. In Montana, the Hell Creek Formation overlies the Fox Hills Formation and is the uppermost formation of the Cretaceous period, it is a series of fresh and brackish-water clays and sandstones deposited during the Maastrichtian, the last part of the Cretaceous period, by fluvial activity in fluctuating river channels and deltas and occasional peaty swamp deposits along the low-lying eastern continental margin fronting the late Cretaceous Western Interior Seaway. The climate was mild; the iridium-enriched Cretaceous–Paleogene boundary, which separates the Cretaceous from the Cenozoic, occurs as a discontinuous but distinct thin marker bedding within the Formation, near its uppermost strata. The Horseshoe Canyon Formation is up to 230 m in depth, it is Late Campanian to Early Maastrichtian in age and is composed of mudstone and carbonaceous shales. There are a variety of environments.
The Horseshoe Canyon Formation outcrops extensively in the area of Drumheller, Alberta, as well as further north along the Red Deer River near Trochu, in the city of Edmonton. The Sarir field was discovered in southern Cyrenaica during 1961 and is considered to be the largest oil field in Libya, with estimated oil reserves of 12 Gbbl. Sarir is operated by the Arabian Gulf Oil Company, a subsidiary of the state-owned National Oil Corporation; the Sarir stratigraphic column resembles succession patterns throughout the Sirte Basin, with some variations. In the early regressive phase, basal sandstones were deposited on a Precambrian basement of igneous and metamorphic rocks. Sandstones are dated on angiosperm pollen as younger than Albian from the Late Cretaceous. After a lengthy hiatus, represented by unconformity and sandstone erosion, a transgressive sequence of red and purple Anhydrite shales was laid. Variegated bed remnants occur in crestal sections of many northern structures, such as
Lithostrotia is a clade of derived titanosaur sauropods that lived during the Early Cretaceous and Late Cretaceous. The group was defined by Unchurch et al. in 2004 as the most recent common ancestor of Malawisaurus and Saltasaurus and all the descendants of that ancestor. Lithostrotia is derived from the Ancient Greek lithostros, meaning "inlaid with stones", referring to the fact that many known lithostrotians are preserved with osteoderms. However, osteoderms are not a distinguishing feature of the group, as the two noted by Unchurch et al. include caudal vertebrae with concave front faces, although the farthest vertebrae are not procoelous. In 1895, Richard Lydekker named the family Titanosauridae to summarize sauropods with procoelous caudal vertebrae; the name Titanosauridae has since been used, was defined by Salgado and colleagues, Gonzalaz-Riga and Salgado as node-based taxon. According to a proposal by Wilson and Upchurch looks today much of the research on the use of that name from: Wilson and Upchurch published a revision of the genus Titanosaurus and declare the type species Titanosaurus indicus as invalid because it is based only on two vertebrae of the tail, showing no diagnostically usable features.
These authors consider ranking groups that are based on Titanosaurus as the nominal taxon, Titanosauridae and Titanosauroidea - considered invalid. In 2004 Upchurch and colleagues presented the new group Lithostrotia to describe the same group as Titanosauridae, but instead it was not based upon a specific taxon; the name Lithostrotia is not recognized by all researchers. Upchurch and colleagues define the Lithostrotia as a node-based taxon that includes the last common ancestor of Malawisaurus and Saltasaurus and all descendants of that ancestor. According to this definition the Lithostrotia includes all forms that are more derived than Malawisaurus in phylogenies. In addition to defining the group Upchurch and colleagues gave two common derived features, which serve to distinguish the group from non-members; the first is that all caudal vertebrae apart from the farthest distal were procoelous, meaning their front face was concave. The front caudal vertebrae were strong procoelous; this first feature is shared with Mamenchisauridae.
Unchurch et al. named Lithostrotia based on the presence of osteoderms in many members, but the eponymous osteoderms do not represent synapomorphy, as the evolutionary history of osteoderms is unknown within the titanosaurs. It may be this trait has developed multiple times independently within the titanosaurs and Lithostrotia, as osteoderms are known in many saltasaurids, Aeolosaurus and various other genera both within and outside Lithostrotia with different morphologies. Lithostrotia is a derived group of titanosaurs, excluding primitive forms such as Andesaurus and Phuwiangosaurus; the equivalent clade Titanosauridae was positioned in a phylogenetic analysis by Calvo et al. where it included all titanosaurs apart from Andesaurus, though multiple primitive forms were not analyzed. Other phylogenies, by Unchurch et al. instead have found a few, non-lithostrotian titanosaurs, or nearly all non-brachiosaurid titanosauriformes within the group. Poropat et al. conducted a similar analysis to one of Unchurch et al..
This analysis found that Andesaurus and Epachthosaurus were within Titanosauria but outside Lithostrotia, the latter group included Malawisaurus, Diamantinasaurus and Alamosaurus as basal lithostrotians outside Saltasauridae. The results of their analysis is shown below. Another phylogenetic analysis in 2016 reproduced below, found Diamantinasaurus as a non-lithostrotian titanosaur and the sister taxon of the contemporary Savannasaurus